A High Precision Multiple Loop Control Strategy for Three Phase PWM Inverters

This paper presents the analysis and design of a multiple-loop feedback control scheme for three-phase voltage source inverters with L-C filters. In the proposed control scheme, a PI regulator in the outer voltage loop and a P regulator in the inner current loop are incorporated, and a plug-in repetitive controller is adopted to improve steady-state performance. Through theoretical analysis, it can be proved that dual-loop controller realizes arbitrary pole placement and thus the design procedure is greatly simplified. The overall control scheme proves superior in suppressing load current disturbance, thus can maintain output symmetry even under unbalanced condition